<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
    <input type="text" id="ipt">
    <script>
      // var tel=prompt("请输入电话号码");

        var ipt=document.getElementById("ipt");

        ipt.onblur=function(){
            var reg=/^1[3-9]\d{9}$/;
            if(!reg.test(this.value)){
              alert("您输入的手机号不正确，请重新输入！");
              return false;
            }

        }
        
       


    </script>
</body>
</html>